Take-off control and method



May 28, 1940 R. H. FLEET ET AL TAKE-OFF CONTROL AND METHOD Original Filed April 24, 1937 4 Sheets-Sheet l YSQ May 28, 1940. E. H. EEEET ET AE 2,202,449

TAKE-OFF CONTROL AND METHOD Original Filed April 24, 1937 4 Sheets-Sheet 2 May 28, 1940. R, HI FLEET E1- AL 2,202,449

' TAKE-OFF CONTROL AND METHOD original Filed April 24, 1937 4 sheets-sheet 5 H66 y l i, Ffa?,

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7 y zf/ @Mm/@MMM May 28, 1940. E. H. FLEET ET AL 2,202,449

TAKE-OFF CONTROL AND METHOD Original Filed April 24, 1937 4 Sheets-Sheet 4 Patented May 28, 1940'v UNITED STATES I PATENT- OFFICE 2,202,449 TAKE-OFF coN'raoL AND METHOD ReubenH. Fleet, William B. vWheatley and Isaac M'. Laddon, San Diego, Calif.'

'13 claims. V(o1. 244-63) Our invention relates to the launching of airplanes, and more particularly to the launching of airplanes from moving vehicles.

This application is a division of our'copendl ing application Serial No. 138,844, led April 24,

Heretofore there have been no edicent means of control ofv take-off of an airplane, other than the skill of the pilot.

10 Often a heavily laden plane will travel down a eld, without rising in the air, a distance greater than it should travel before the brakes are applied. This mistake in judgment on the part of the pilot often results in accidents.

One object of the invention is to provide .an automatic means for preventing take-oil' after a i employing our invention;

certain distance of run if ample air speed has not been attained at a certain predetermined point in. the run.

'l Another object of the invention is to. provide air speed control for' releasing an airplane from a vehicle on which it is mounted for launching.

Still another object ol.' the invention is to provide an electrical circuit which controls the re- 29 lease of an airplane from a launching vehicle.

Yet another object of the invention is to provide an automatic means for applying the brakes on a vehicle carrying an airplane for launching at a certain point in its run. 30 A further object of the invention is to provide a novel form of hold-back mechanism by which the airplane is fastened at a point at the beginning of its run while the motors are being warmed up. 35 A still further object of the invention is to provide an air pressure switch for controlling the operating mechanism, such control depending on the air speed for which the device is set.

Yet a further objectf of the invention is to provide novel hold-down members by which an airplane is held to a launching vehicle.

Still a further object of the invention isv to provide means for holding down the nose of an airplane during the take-01T run until the proper air speed is reached for the airplane to take off from the vehicle.

Another object of the invention is to permit the launching of airplanes without human attention, or at least wihout skilled handling during he take-ofi run until after-the plane leaves the vehicle. tomatic take-off is especially valuable for flights controlled by robot pilots.

With these and other objects in view, which may be incident to our improvements, the inven- In this connection the completely-aution consists in the parts and combinations to be hereinafter set forth and claimed, with the una derstanding that thel several necessary elementsv comprising our invention may be varied in construction, proportions and arrangement, without departing from the spirit and scope -of the appended claims.

In order to make our invention more clearly understood, We have'shown in the accompanying drawings means for carrying the sameinto pracl0 tical effect Without limiting the improvements in their useful applications to the particular constructions which, for the purpose of explanation, have been made the subject of illustration. y

- In the drawings: 16

Figure 1 is a diagrammatic View of a system ,Figure 2 is a view in side elevation l,of a sea'- plane mounted on my supportingvehicle, part of the supporting vehicle being broken away to show the construction;

Figure 3 is a view in front elevation of a seal plane mounted on the supporting platform of the vehicle, showing the hold-down means by which the seaplane is held attached to the vehicle with its nose down;

Figure 4 is a detail view partly in sectionof the holding means for the seaplane.

Figure 5 is a detail sectional view showing the holding means removed from lits socket in the wall of the seaplane.

Figure 6 is a view taken along the line 6-6 Iof Figure 4;

Figure '7 is a view taken along the line 1-1 of Figure 4.

Figure 8 is a diagrammatic view of the control circuit for releasing the seaplane from the supporting vehicle.

Figure 9 is a sectional View taken through our control switch operated by air speed. 40

Figure 10 is a detail perspective view of the control for `the brake mechanism.

of the track which supports the launching ve hicle by means of a cable.

The motors of the airplane are warmed up and 'the running full throttle (or desired power outson of hold-down members which are attached to the supporting vehicle. When a proper air speed is reached, the hold-down members for the nose of the airplane are released, and the fact that the center of gravity of the airplane lies behind the pivot of the cradle on which the airplane rests, in addition to the fact that the elevators are s et to raise the nose of the airplane, causes the airplane to quickly assume a substantially high angle of attack attitude, and the airplane will then duiclrly take oi from the supporting it a certain point in its run, a trip at the side or" the traclr automatically applies the brakes to the vehicle on which the airplane is supported. 'llhe location of this trip may be varied as reduired. if the airplane has not taken oir from the Vehicle when this point is reached, both airplane from the vehicle.

airplane and vehicle are then arrested. However, if the airplane has taken off from the vehicle, the braises will stop the vehicle. An arresting cable at the end of the run prevents overrunning of the vehicle beyond the end of the track. l

Referring to the drawings, in Figure 1 we have shown an airplane l' mounted on a platform 2 of a vehicle The vehicle 3 is adapted to travel on tracks d. In Figure l the airplane l is shown held by a cable d at one end of the track. The

motors of the airplane are warmed up, and whenI they are running at desired power output the pilot releases the cable t, as will be later described, and the airplane runs down the track, gaining speed. The elevators of the airplane are set in the position to raise the nose of the airplane. The nose is held down by holding means until the air speed is sumcient for the taire-ofi of the The section of the track on which this will normally occur is indicated in the drawings, Figure l.

If the airplane takes'oi before the point in Figure 1 Where it is indicated that the car brakes are applied, the vehicle is merely arrested by the application of the brakes, overrunning being prevented by the arresting gear.

`We have indicated the section of track on which take-off usually occurs by the numeral 6, the point at which the car brakes are applied as numeral l, and the arresting gear to prevent overrunning of the vehicle by the numeral d.

If sumcient air speed is not attained for the take-'01T of the airplane from the vehicle by the 'time the vehicle reaches the position indicated by the numeral "l, the car brakes are applied and the vehicley with the airplane on it, is arrested.

Referring to Figure 2, l have shown the airplane i as a s'eaplane. llt is adapted to be mounted in a'cradle 9 which is pivoted on a shaft lli mounted in supports li which are attached to the surface of the platform i2. n either Aside of the airplane, and pivoted at points i2 to the upper surface 2 of the vehicle il, are holding members i3 which are adapted to hold the nose Ml of the airplane down, as indicated in rieure 2.

v member 25.

` abonnee in Figure 2 ll have shown an elevator l5 in a normal position. At the beginning of the run the elevator l5 is generally set in a position to raise the'nose lll of the airplane. The center of gravity of the airplane is somewhat back of the pivot shaft lil, tending to raise the nose and lower the tail, but the holding members i3 on either side of the plane prevent this from happen.- ing until they are released. Additionally, the setting of the elevators when a substantial forward speed is obtained tends t0 raise the nose ld.

In Figures 3 to 7 inclusive are shown the details of the holding means for holding the nose lf3 of the airplane in the substantially zero angle of attack attitude, or nolift.attitude. Each hold ing member it comprises a bifurcated construc tion comprising arms l@ which are joined together at their top at il and which are pivoted at their bottom at points 02 on supports iii carried on the upper surface or platform 2 of the vehicle tl.

Each of the arms l@ is provided with an outwardly projecting lug it] which is adapted to contact a base 2@ formed on each of the supports lil. The lugs i9, in contacting the base 26D, hold the holding members i3 in the position indicated in Figure 5. This position permits the airplane to take off from the platform 2 while at the same time the holding members i3 are prevented from falling to a position whe're they might encounter obstacles on the side of the track.

On either side 2l of the hull of the flying boat l we have provided a double wall construction 22. A base member 23 on either side oi the hull encircles an aperture 2d in which is mounted, on

the outside of either side of the hull, a plate 25. On the inside of the aperture it on either sideof the hull is mounted a holding plate 26. Plate 25 is held to the holding plate 26 by bolts or any other suitable device. Each plate 25 is provided with a rustoconical aperture 2l in which is adapted to fit a frustoconical male member 28 carried at the top ll of each holding member (I3.

Each frustoconlcal male member 28 comprises a movable section 29 which is pivoted at 30 in the top ll. Each section 29 is provided with a locking nose 3l.

A spring 32 mounted on the top lll of each holding member i3 lies against a lip 33. Each spring 32 tends to hold each member 29 in the positionshown in Figure 4.

lin the position shown in Figure 4, each locking nose 3l projects into an aperture 35 formed in the member t5 and holds the holding member firmly in place, locking the nose M of the airplane l in the down or substantially zero angle of attack attitude'.

In order to release each holding member I3 from its locking engagement with the hull of the flying boat, we have provided a trip mechanism which pushes down on each locking nose 3l to release it from its respective aperture 35 in each Each holding member I3' is pushed over into the position shown in Figure 5 by meansl of springs 36 attached at 3l on the top I 1 of the holding members. The springs 3S push against theouter faces of the members 25 to push the holding members i3' away from `their holding position upon release of the locking nose @l of the male member 28.

, Each locking nose 3l lis adapted in its locking position to contact the lower side of a lever arm 38 pivoted at 39 of each holding plate 36. Each lever has an arm t@ which is pivoted at 4l to a connecting link 42 which is pivoted at 43v to the core 44 of a solenoid. The solenoid winding 45 is shown mounted 0n a supporting bracket 46 which is attached at 41 to each plate 26.

When the solenoid winding 45 is energized, uit pulls up on the solenoid core or armature 44, which rocks the lever on the pivot 39 to cause the arm 38 to assume the position shown in Figure 5 which pushes the movable pivoted section 29 of the male member 28 down against the tension of the spring 33 and permits the frustoconical .male member 28'to come Vout of engagement with the frustoconical aperture 35.

At the same time, a cut-out switch has been .operated to cut out the flow of electricity to the operating coils 45 of the solenoids. On each side 2| of the hull of the flying boat, we have mounted on plates 26 a casing 48 of the cut-out switch, the details of which are not shown, but which is diagrammatically illustrated in Figure 8 at 49.

There is adapted to slide into the casing 48 an operating plunger 50 having a head 5| and a spring 52 which tends to urge the head 5| into the position shown in Figure 5. When the holding member I3 is in the engaging position shown in Figure 4, spring 52 is compressed, and the cut- 'out switch-49 permits the passing ofcurrent.

With the parts in the position shown in Figure 5, the cut-out switch does not permit the passing of current, thus saving drain on the operating battery or other source of electromotive force used on the -airplane and the overheating of the coils 45.

The operation of the release of the holding members i3 is accomplished by means of air speed (see Figures 8 and 9). On the front of the airplane are mounted a Venturi tube and a pressure tube 6|. The Venturi tube 60 is connected at its throat 62 with a pipe 63 which connects at 64 to one side 65 of an airtight container having a flexible diaphragm 66 mounted in the middle. The pressure tube 6| is connected by means of a tube 61 and a connection 68 to the other side 69 of the airtight container 65. Movement of the tubes through the air causes an aslci) pirating effect to be produced by the Venturi tube 60 which produces a suction at the throat 62. 'Ihe air passes through the venturi due to the motion of the airplane in the direction'indicated by the horizintal arrows, Figure 8. Air is aspirated, as indicated by the arrows, through the tube 63 from air chamber 65, reducing .the pressure one one side of the flexible diaphragm 66.

' At the same time, air is forced down the pressure tube 6I, as indicated by the arrows, through tube 61 into the pressure side 69 of the chamber 65.

It is to be understood that instead of pressure and Venturi tubes-Pitot (pressure) and static tubes-as at present used to actuate air speed indicators could be used. l

A reduction of pressure on one side of the diaphragm 66 and an increase 'of pressure on the other causes the diaphargm 66 to flex.

The diaphragm 66 carries a contact 10 which is adapted to contact with a contact 1| carried on the spring 12. When this'contact is made between contacts 10`and 1I, a shunt circuit is closed, which causes energization of the coils 45 of the solenoids to cause release of the male members 28 in their sockets 21 to release'the holding members I3 from their holding function on the airplane.

The operation of the circuits will be apparent :from an inspection of Figure 8. The closing of contacts 10 and 1| closes a shunt'circuit comprising leads 18, high resistance coil 14, cut-out switch `49, lead 15, to battery 16, through lead 11 attached to the other pole of the battery 16, to contact 10.V

Instead of battery 16, any other suitable source of electromotive force may be employed. Mechanical, hydraulic, or pneumatic devices, instead of electrical, could be employed to give the same result.`

The circuit just described is a shunt circuit and, because of the high resistance of the coil 14, a small amount of current traverses this circuit. 'I'he circuit is opened onthe opening o! cut-out switch 49. The main circuit comprises a lead 18 connected to lead 15 and a lead 19. The coils 45 of the main operating solenoids are connected across the leads 18 and 19. Through tacts 82 and 83, a circuitis completed from the source of electromotive force 16 through the coils 45 of the operating solenoids. Thus, when a suiilciently high air speed is attained, automatically the circuits just described cause energization of the solenoid windings 45 which raise the solenoid armatures 44-to release male members 26.from frustoconical sockets 21. The springs 36 cause the holding members I3 to be pushed away from the sides 2| of the hull of the flying boat, and the airplane is free to take off from the cradle. The cradle 9 is rocked back on its pivot I0 by reason of the fact that the center of gravity of the airplane is behind the pivot I0 and also because of the setting of the elevators I5 to raise the nose |4. Since ilying speed has been attained before the nose I4 rises, the airplane will quickly take oil? from the cradle and leave the launching vehicle 3.

rlhe details of the construction of the airtight container will now be given. Referring particularly to Figure 9, it will be seen that the airtight container 65 comprises two halves |00 and I0| which are joined together by suitable screws |02, only one of which is shown in the drawings. The iiexible diaphragm 66 is held between airtight packing rings |03 which lie on either sidel of the periphery of the flexible diaphragm 66. The screws |02 hold the two halves |00 and |0| together, and also hold the exible diaphragm66 in place.

` The top screw |02 is adapted to hold an insulating support |04 which carries a screw |05 which is electrically connected through a lead |06 to the flexible diaphragm 66. The screw |05 carries nuts |01 to whicl is adapted to be attached lead 11 (see Figure 8).

The half of the casing IOI is provided at its top with an aperture |08 which has an airtight b e attached lead 13 (see Figure 8).

Held against the insulating washer III on the inside of the casing by the head of the screw or bolt IIO is the bent-over end ||4 of the exible resilient metallic strip 12 which is bent at ||6 to form a flexible end I|1 lthat carries the y contact 1I. l

The half |0I of the metallic casing 65 is'pro.- vided with a packing gland indicated generally by the numeral its, through which is adapted to reciprocate-a rod lili.- One end oi the rod il@ contacts an insulating member |120 which is attached at |2l to the flexible metallic strip 12. Attached by screws l22 to the outside of the` half of the airtight casing t5 is a support spider |23 which is screw threaded at l24 to receive a screw threaded section H25 of the rod ||9 which has a knurled adjusted head i21. A lock nut |28 on the screw |26 is adapted to hold the rod ||9 in a desired'adjusted position so as to increase or decrease the distance between contacts 1| and 10 to adjust the device for varying desired air speeds.

Pipe 69 from the air pressure tube 6| is adapted to be attached to a connection (|30 to the half |00 of the airtight casing 65, and to a connection |3| is adapted to be attached pipe 64 from the Venturi tubeGO.

The functioning of this apparatus has been previously given in connection with the description of the circuit (Figure 8). llt is obviousthat, by adjusting the position of the rod M9, the device may be set for varying air speeds.

The method of applying thebrakes on the l vehicle at a certain predetermined point in the run will now be described. Referring briefly to Figure 1, it has been explained .that at point 1 the brakes are applied on the vehicle. In Figure l 2 and Figures 10 and 11 is shown the mechanism for applying the brakes on the vehicle. There is provided an air tank 200 which is adapted to receive air under pressure from inlet pipe 20| having a one-way iilling valve Y202. The pipe 20| communicates with a pipe 203. There is a shut-off valve 204 provided in the pipe 203. Air under pressure can be sent in to the tank 200 through valve 202. pipe 203 which communicates with an operating valve which is indicated generally by the numeral 205. The operating valve also communicates through a pipe 206 with a pipe 201 which goes to the brake cylinders.

The brake cylinders are of the vehicle 3 and areconnected to the pipe 201 through pipe 200. The brake cylinders we have indicated in Figure 2 by the numeral 209. Through suitable operating linkage connections indicated generally by the numeral 2 |0 the brake shoes 2|| may `be applied on admitting air to the brake cylinders 209. The details of this construction are shown in our copending application Serial No. 112,803, tiled November 25, 1936, and it is not thought necessary to repeat the detailed description therein contained.

The` valve 205 comprises a valve casing 2|2 and a rotatable member 2M therein which has y a three-way connection, namely, a duct 2id, a duct 2|5 and a duct M6. Attached to the rotatable member 2i3 is a connection shaft 2li which is provided with a crank 2in and a contact member 213.

,The contact member 269 is adapted to strike a trip 220 set in a vsupporting base 22. rihe trip 220 is located at the point designated by numeral 1 in Figure l. As the vehicle passes the station 1, the trip 220 strikes contact niember 2|9 and rotates the rotatablelrnember 2id of the valve.

With the parts shown inwtheposition indicated in solid lines in Figure ll, the brakes exhaust through ducts 234 and 2lb. With the parts shown in the position indicated in dotted lines in Figure V1li., air passes from the container 2t@ through duct 265 and duct 2i@ to pipe Edt,

Connected to pipe 203 is ak located at either end decente thence to pipe 2011 and thence to brake cylinders 209 to apply the brakes. A

Thus, as the launching vehicle4 3 passes point 1, the brakes are applied.

Full application of brakes might slide the wheels-causing lossv of braking eiilciency and wearing fiat spots on the wheels, though automatic control of brake application (as used on new streamlined trains) could be used. Such automatic control works on deceleration forces on the vehicle. f

In order to insure the stopping of the vehicle, we have provided cable engaging members 223 at either end of the vehicle 3. These members comprise a throat construction 224 in which the passed into the throat 224. Thus, if the brakes have not stopped the vehicle, which may or may not support the airplane at this point in the run, depending upon whether orA not the airplane has taken off from the launching vehicle, the vehicle will be arrested bythe arresting cable 8 at the end of the run.

The details for applying brakes toA the arresting cable are Well known, and it is not believed necessary to describe them. -Details of one form of arresting cable construction are shown in our copending application Serial No. 105,611, filed October 14, 1936.

The hold-down mechanism for holding the airplane in lthe beginning of the run will now be described. Referring to Figure 1, we have shown that there is a cable 5 which holds the airplane at the beginning of the run until the motors are running full throttle, at which time the pilctreleases the cable 5 from the airplane, and the airplane and the launching vehicle, prei'- erably only under the power of `the ,motive power plant of the airplane, proceed down the rail track 4.

The cable 5 is attached to an anchor membe 300 which may be mounted between the rails of the rail track- 4. The cable 5 has a loop 30| which is adapted to pass through an aperture 302in a male member 303 which is adapted to slide in a slideway 304 formed in a support member 305 which ts within an aperture 306 formed in the bottom 301 of the fuselage. The aperture 306 is braced by means of a bracing member 308 which acts as a support vfor the strain imposedby vforces acting through the support member 305.

Pivoted on the support member 305 on a pivot 309 is a fastener 3|0. The fastener 3|0 is pro` vided with a catch 3|| having a sloping surface SI2 which is adapted to engage a sloping surface M3 formed on the end of the male member 303. A coil spring 3M is adapted to urge the fastener 3i@ in the up, or disengaging, position. *The slope of the surfaces SI2 and "3|3 is such as to tend to move the fastener 3|0 in the up, or disengaged, position. In order to hold the fastener Siti in the down, or engaging, position, there is provided a release member 3l5 which/is pivoted on a pivot :titi supported by the socket '305. One arm till of the release member '355 isndapted .to bear against the top of the fastener The other arm @it of the release member 3|5 is'held in the position indicated in solid lines in Figure 12 by means of a spring di@ which is attached to the arm dit and to the fuselage 301. A

cable 320 is pivotally attached at 32I through a suitable connection 322 to the arm 3|8 of the release member 3l5.

A stop 323 prevents the spring 3I9 from moving the release member beyond the position shown in solid lines in Figure l2. Upon the pilot pulling on cable 320, the release member 3| 5 is pivoted on its pivot 316 against the tension of the spring :H9 to move the arm 3| 1 out of engagement with the,i top of the fastener 3H). The fastener 3|!! is raised to the position shown in dotted lines in Figure 12 under the tension of the spring 3|4and because of the forces exerted by the engaging surfaces 3|2 and 3I3. The airplane is then freed from the hold-down mechanism and can proceed on its run.'

In operation, the airplane, with its nose held down in the substantially no-lift attitude, is resting on the dlaunching vehicle 3 at the beginning of the run, as indicated in Figure l. The cable 5 holds the airplane and the supporting vehicle from forward-movement while the engines are being warmed up and until they are running full throttle. The elevators l5 are set to lift the nose of the airplane, but are prevented from functioning until the nose of the airplane is no longer held down by the holding members I3.

When the motor is running full throttle, or at desired power output, the pilot pulls on cable 220 and releases the airplane and vehicle which, under the power of the motive power plant of the airplane, runs down the rail tracks 4 until sumcient air speed is attained for the closing of contacts 10 and 1|. l

'I'he closing of these contacts releases the holding members I3, as previously described, and permits the airplane to rock back on the cradle 9 and to quickly take off from the launching vehicle. is opened to prevent drain on the batteries and overheating of the coils 45.

As the vehicle passes the trip mechanism lolcated at 'l along the track, the brakes are applied and, in case the vehicle ls still moving, they arresting cable 8 will stop the vehicle.

If suiilcient air speed has not been attained during the run and before the point 1 is reached ,on the track, the nose of the airplane will be held down in the position indicated in Figure 2 and the airplane cannot take oif from the supporting vehicle. L

Thus, automatic control of take-off is substituted for the pilots judgment, and safety factors are introduced into the launching of airplanes-y which have never heretofore been possible.

With ournvention no human attention is required to safely get the aircraft into the air;

in fact if a robot pilotsuch as the Sperry automatic airplane -pilot were used on the airplane,

no human need even be aboard .the aircraft (this might be desirable in time of war in the case of a very dangerous mission where the airplane would be expended to accomplish the mission). Also in time of war, planes might be launched with our invention, manned byvcrews not sunlciently'skilled to Vmake safe take-offs in the normal way, yet who could guide the .plane in flight, and could probably land the plane, which would be much lighter after returning from. a mission, without damaging it,

The arrangement of the device to automati-` cally launc an airplane would be such that the relation of the supports and the center of gravity would cause the aircraft to pivot to the take-off attitudewhen the forward support was At the same time, cut-out switch 49 released. With the elevators set for normal climb, or if the automatic (robot) pilot was set for a climbing attitude, then when the forward release was disconnected the plane would automatically take off."

While we have shown and described the preferred embodiment of our invention, we wish it to be understood that we do not confine ourselves to the precise details of construction herein set forth by way of illustration, as it is apparent that many changes and variations may be made therein, by those skilled in the art, without departing from the spirit of the invention, or exceeding the scope of the appended claims.

We claim:

1. In an airplane having means to lock it to a vehicle, a control mechanism to release the locking means comprising a casing, a diaphragm in the casing, a contact carried by the diaphragm, a second -f contact adjacent the diaphragm, a Venturi tube for /lessening the pressure 'on one side of the diaphragm, a pressure tube for increasing the pressure on the other side of the diaphragm, and means to adjust the initial distance between the contacts to prevent closing of the contacts until a predetermined air speed is reached. 1

2,. In an airplane having means to lock it to a vehicle comprising a source of current, electromagnetic means for effecting release of the airplane from the vehicle, means for connecting the source of'current and the electromagnetic means, a switch for controlling theflow of current to the electromagnetic means comprising contacts movable relative to each other, means to cause such relative movement of the contacts depending on the air speed, and means to adjust the initial distance between the contacts to prevent closing of the contacts until a predetermined air speed is reached.

3. In an airplane having means to lock it to a vehicle comprising a source of current, electromagnetic means for effecting release of the airplane from the vehicle, means for connecting the source of current and the electromagnetic means, a switch for controling the flow of current to the electromagnetic means, control means for said switch, a Venturi tube, a pressure tube, and

`tubing connecting the pressure tube and the throat of the venturi to the control means whereby the control means is operated only upon a predetermined air speed. I

4. In an airplane having means to lock it to a vehicle comprising a source of current, electromagnetic means for eifecting release of the aira predetermined air speed, and adjustable regullating means for setting the control means to operate the switch at the desired air speed.

5. In an airplane having means to lock it to a vehicle comprising a source of current, electromagnetic means for eecting release of the airplane from Athe vehicle, means for connecting the source of current and the electromagnetic means, a switch for controlling the flow of current to the electromagnetic means, a diaphragm element for operating said switclngal Venturi tube, a pressure tube, and tubing connecting the pressure tube and the throat of the venturi to opposite sides of the diaphragm element, whereby the switch is operated only upon a predetermined air speed.

6. In an airplane having means to lock it to a vehicle comprising a source of current, electromagnetic means for effecting release of the airplane from the vehicle, means for connecting the source of current and the electromagnetic means, a switch for controlling the ow of current to the electromagnetic means, a diaphragm element for operating said switch, aVenturi tube, a pressure tube, tubing connecting the pressure: tube and the throat of the venturi to opposite sides of the diaphragm element, wherebythe switch is operated only upon a predetermined air speed, and adjustable regulating means for setting the control means to operate the switch at the desired air speed.

'7. In an airplane, having means for locking it to a vehicle and means for releasing the locking means upon attainment by the airplane of a predetermined air speed comprising a release solenoid, a switch for electrically controlling the release solenoid, an expansible chamber for moving by its contraction said controlling switch toward closedl position, a second expansible chamber for moving by its expansion said controlling switch toward closed position, the two expansible chambers being opposed in action so that a pressure differential therein will actuate said controlling switch, a Venturi tube and a Pitot tube carried on'an air-stream surface of the airplane, hollow connecting means for connecting the Venturi tube to the iirst mentioned chamber, and a second connecting means for connecting the Pitot tube to the second mentioned chamber, and a source of electric current connected for operation of the release solenoid, said current being controlled by said control switch.

8. In an airplane, having means for locking it to a vehicle and means for releasing the locking means in accordance with the air speed of the airplane comprising a casing, a 4iiexible diaphragm for separating the interior of the casing into two compartments, the casing having apertures owably connecting each of said compartments, a contact point carried by the flexible diaphragm at a point where Variations of pressure between the two chambers will induce movement of the contact, a resilient electrical conductive member positioned in one of said compartments, the resilient member carrying an electrical contact point at its free end and adapted to be touched by the contact carried by the diaphragm,means to conduct electric-current from the resilient member to the outside of the casing and a second conducting means to carry current from the diaphragm contact member to'a point outside the casing, said conducting means being insulated electrically from one another, means connected to the two compartments through said apertures and adapted to produce a pressure diierential in the two compartments in response to the speed of the airplane, a release solenoid, and a source of electric current connected for operation of the release solenoid, said current only passing said contact points to form an electric contact.

9. In an airplane, having means for locking it to a vehicle and means for releasing the locking means in accordance with the air speed. of the airplane comprising a release mechanism, a switch for electrically controlling the release aaoaaco mechanism, apparatus responsive to a uid pressure diierential to close said actuating switch, means connected to said apparatus adapted to produce said diiferential in response to the speed of the airplane, means to lock the airplane to the vehicle, means vcarried by the airplane to Y engage said locking means, said engaging means being disengaged by the release mechanism, a cut-oil rod, a cut-on switch adapted to close by pressure of said rod and adapted to open upon release of said pressure, means to resiliently urge said rod toward said locking means engaged by said engaging means, whereby upon the release of said locking means through actuation of the release mechanism the cut-off switch will be opened, and a source of current connected through said controlling switch, and the cut-oi switcli to the release mechanism.

10. In an airplane, having means for locking it to a vehicle and means for releasing the loclr-A ing means in accordance with the air speed o f the airplane, a release mechanism, a switch for electrically controlling the release mechanism, means responsive to the speed of the airplane to close said actuating switch, means to lock the airplane to the vehicle, means carried by the airplane to engage said locking means, said engaging means being disengaged by the release mechanism, a cut-off rod, a cut-oi switch adapted to close by pressure of said rod and adapted to open upon release of said pressure, means to resiliently urge said rod toward said locking means engaged by said engaging means, whereby upon the release of said locking means through actuation of the release mechanism the cut-oi switch will-be opened, and-a source of current connected throughl said controlling switch and the cut-off switch to the release mechanism.

11. In an airplane, having means for locking. it to a vehicle and means for releasing the locking means in accordance with the air speed of the airplane comprising a casing, a ilexible diaphragm for separating the interior of the casinginto two compartments, the casing having apertures entering each of said compartments, a contact point carried by the iiexible diaphragm at a point where variations of pressure between the two chambers will induce movement of the contact, a lresilient electrical vconductive member positioned in one of said compartments, the resilient member carrying an electrical contact point at its free end and adapted to be touched by the contact carried by the diaphragm, means to conduct electric current from the resilient member to the outside of the casing and a. second conducting means to carry current from the diaphragm contact member to a point outside the casing. said conducting means being insulated electrically from one another, means connected to the two compartments through said apertures and adapted to produce a pressure differential in the two compartments in response to the speed of the airplane, means to lock the airplane tothe vehicle, means carried by the airplane to engage said locking means, a release mechanism to disengage said engaging means, a cut-off, rod, a cut-oi switch adapted to close by pressure of said rod and a'dapted to open upon release of said pressure, means to resiliently urge said rod toward said lockingmeans engaged by said engaging means, whereby upon the release ci said locking means through actuation of the release mechanism the cut-oi switch will be opened, and, a source of current connected through said conducting means and said contact points and the cut-off switch to the release mechanism.

12. In an airplane, having means for locking it to a vehicle and means for releasing the locking means in accordance with the air speed of the airplane comprising a casing, a exible diaphragm for separating the interior of the casing into two compartments, the casing having apertures entering each of said compartments, a contact point carried by the flexible diaphragm at a point where variations of pressure between the two chambers will induce movement of the contact, a resilient electrical conductive member positioned in one of said compartments, the resilient member carrying an electrical Contact point at its free end and adapted to be touched by the contact carried by the diaphragm, means to conduct electric current from the resilient member to the outside of the casing and a second conducting means to carry current from the diaphragm contact member to a point outside the casing, said conducting means being insuadjustment piece from the, resilient member,`

means to maintain a predetermined setting of the adjustment rod, means to prevent leakage of air through the casing wall at the adjustment rod, means to lock the airplane to the vehicle, means carried by the airplane to engage said locking means, a release mechanism to disengage said engaging means, a cut-off rod, a cut-off switch adapted to close by pressure of said rod and adapted to open upon release of said pressure, means to resiliently urge said rod toward said locking means engaged by said engaging means, whereby upon the release of said locking means through actuation of the release mechanism the cut-oir switch will be opened, and a source of current connected through said conducting means and said contact points and the cut-01T switch to the release mechanism.

13. A switch responsive to movements of an air stream comprising a casing, a diaphragm positioned for separating the interior'of the casing into two compartments, the casing having apertures entering each of said compartments, a contact point carried by the exible diaphragm at a point where' variations of pressure between the two chambers will induce movement of the contact, a second contact point, means to position the second contact point near the diaphragm-carried contact and in line with the movements of the diaphragm-carried contact, means to conduct electriccurrent from the contact points to separate positions outside of the casing, said conducting means being insulated electrically from one another, means for separately connecting each of said compartments for ow to or from pressure varying apparatus. 

